+ /* Filter out `bad' characters which cause problems with some systems.
+ There's no apparent list of what really is allowed, so this is a guess.
+ */
+
+ string filtered;
+ string const allowed = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_";
+ for (size_t i = 0; i < unfiltered.size(); ++i) {
+ if (allowed.find (unfiltered[i]) != string::npos) {
+ filtered += unfiltered[i];
+ }
+ }
+
+ return filtered;